Dec 7 (Reuters) - Cryptocurrency marketplace NiceHash said
the contents of its bitcoin wallet had been stolen in a security
breach and one executive said nearly $64 million had been lost.

NiceHash head of marketing Andrej P. Škraba told Reuters on
Thursday that the hack was "a highly professional attack with
sophisticated social engineering" and that about 4,700 bitcoin,
worth about $63.92 million at current prices, were lost.

He said the company was co-operating with local authorities
but declined to give more information.

Earlier, Slovenia-based NiceHash said in a statement posted
on its website that it had halted operations for 24 hours as it
investigated the breach.

NiceHash is a digital currency marketplace that matches
people looking to sell processing time on their computers in
exchange for the digital currency bitcoin.

NiceHash advised users to change online passwords, saying it
was still trying to understand what had happened during the
incident.

"We understand that you will have a lot of questions, and we
ask for patience and understanding while we investigate the
causes and find the appropriate solutions for the future of the
service," the company said in its statement.
(Reporting by Jeremy Wagstaff in Singapore and Bhanu Pratap in
Bengaluru; Editing by Jim Finkle and Raju Gopalakrishnan)